Iterative adaptive solar tracking having variable step size
View Patent ↗A system controller for position controlling a photovoltaic (PV) panel in a PV system including a power sensor sensing output power (P), and a motor for positioning the PV panel. The system controller includes a computing device having memory that provides motor control signals and implements an iterative adaptive control (IAC) algorithm stored in the memory for adjusting an angle of the PV panel. The IAC algorithm includes an iterative relation that relates P at current time k (P(k)), its elevation angle at k (θ s (k)), P after a next step (P(k+1)) and its elevation angle at k+1 (θ s (k+1)). The IAC algorithm generates a perturbed power value P(k+1) to provide a power perturbation to P(k), and calculates a position angle θ S (k+1) of the PV panel using the perturbed power value. The motor control signals from the computing device cause the motor to position the PV panel to achieve θ S (k+1).
1. A photovoltaic (PV) system, comprising:
at least one PV panel having a panel surface for receiving solar radiation;
a power sensor coupled to an output of said PV panel for sensing an output power (P) provided by said PV panel;
a system controller including at least one computing device having associated memory that provides motor control signals, wherein said computing device is programmed to implement an iterative adaptive control (IAC) algorithm stored in said memory for adjusting an angle of said PV panel;
wherein said IAC algorithm includes an iterative relation that relates said P at a current time k (P(k)), its elevation angle at said k (θ s (k)), said P after a next step (P(k+1)) and its elevation angle at k+1 (θ s (k+1)), said IAC algorithm operable to generate a perturbed power value P(k+1) to provide a power perturbation to said P(k), and calculate a position angle θ S (k+1) of said PV panel using said perturbed power value in said iterative relation;
said system further comprising a mechanical system comprising a motor coupled to receive said motor control signals, said motor control signals positioning said PV panel to achieve said θ S (k+1);
wherein said power sensor senses said P with said PV panel positioned at said θ S (k+1); and
wherein said IAC algorithm further implements:
comparing a change in said P resulting from said positioning to a predetermined P change limit, and
if said change in said P is ≧said predetermined P change limit, repeating said generate, calculate and said positioning, and
if said change in said P<said predetermined P change limit, waiting a predetermined waiting period before next performing said sensing said P.
2. The system of claim 1 , wherein said
predetermined waiting period is 1 to 30 minutes.
3. The system of claim 1 , wherein said iterative relation comprises:
θ
S
(
k
+
1
)
=
θ
S
(
k
)
-
P
(
k
+
1
)
2
-
P
(
k
)
2
2
*
P
(
k
)
.
4. The system of claim 1 , wherein said P(k+1) is generated by the following equation:
P ( k+ 1)= P ( k )+[sgn( P ( k )− P ( k− 1))]*( P ( k )− P ( k− 1))
wherein said sgn is the signum function.
5. The system of claim 1 , wherein said system controller further implements an iterative adaptive control algorithm for iteratively adjusting an azimuthal angle θ AZ of said PV panel.
6. The system of claim 1 , wherein said system other than said PV panel is exclusive of sensors for sensing said solar radiation.
7. A system controller for controlling a position of at least one photovoltaic (PV) panel having a panel surface for receiving solar radiation in a PV system including a power sensor for sensing an output power (P) provided by said PV panel, and a motor for positioning said PV panel, said system controller comprising:
at least one computing device having associated memory that provides motor control signals, wherein said computing device is programmed to implement an iterative adaptive control (IAC) algorithm stored in said memory for adjusting an angle of said PV panel;
wherein said IAC algorithm includes an iterative relation that relates said P at a current time k (P(k)), its elevation angle at said k (θ s (k)), said P after a next step (P(k+1)) and its elevation angle at k+1 (θ s (k+1)), said IAC algorithm operable to generate a perturbed power value P(k+1) to provide a power perturbation to said P(k), and calculate a position angle θ S (k+1) of said PV panel using said perturbed power value in said iterative relation;
wherein said motor control signals from said computing device are operable to cause said motor to position said PV panel to achieve said θ S (k+1)
wherein said power sensor senses said P with said PV panel positioned at said θ S (k+1); and
wherein said IAC algorithm further implements:
comparing a change in said P resulting from said positioning to a predetermined P change limit, and
if said change in said P is ≧said predetermined P change limit, repeating said generate, calculate and said positioning, and
if said change in said P<said predetermined P change limit, waiting a predetermined waiting period before next performing said sensing said P.
8. The system controller of claim 7 , wherein said predetermined waiting period is 1 to 30 minutes.
9. The system controller of claim 7 , wherein said iterative relation comprises:
θ
S
(
k
+
1
)
=
θ
S
(
k
)
-
P
(
k
+
1
)
2
-
P
(
k
)
2
2
*
P
(
k
)
.
10. The system controller of claim 7 , wherein said P(k+1) is generated by the following equation:
P ( k+ 1)= P ( k )+[sgn( P ( k )− P ( k− 1))]*( P ( k )− P ( k− 1))
wherein said sgn is the signum function.
11. The system controller of claim 7 , wherein said system controller further implements an iterative adaptive control algorithm for iteratively adjusting an azimuthal angle θ AZ of said PV panel.
12. The system controller of claim 7 , wherein said computing device comprises a microprocessor.